Binding and activation of aromatic molecules by a molybdenum pi-base

Compounds having the form TpMo(NO)(1-methylimidazole)(eta(2)-L(pi)) (Tp = hydridotris(pyrazolyl)borate; L(pi) = cyclohexene, naphthalene, furan, thiophene, and acetone) were synthesized in 31-41% yield by the reduction of TpMo(NO)Br(2) in the presence of 1-methylimidazole and the respective pi-acidic organic ligand. The structure of the naphthalene complex was confirmed by single-crystal X-ray diffraction. Degradation studies showed the bound aromatics to have half-lives of 37-236 h in acetone solution at 20 degrees C. A tandem addition across the bound ring of the naphthalene complex yielded a free 1,2-dihydronaphthalene in 80% yield following decomplexation.     

固相萃取ICP-AES法测定多种微量元素的研究

建立了以微晶萘作为吸附载体的固相萃取ＩＣＰ－ＡＥＳ法测定微量Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｚｎ、Ｃｄ、Ａｌ、Ｍｎ的新方法。研究了溶液酸度、试剂浓度、萘用量以及共存离子对待测物回收率的影响。方法可用于生物标样品的测定,分析结果满意。     

固相萃取ICP-AES法测定多种微量元素的研究

建立了以微晶萘作为吸附载体的固相萃取 Ｉ Ｃ Ｐ Ａ Ｅ Ｓ 法测定微量 Ｆｅ 、 Ｃｏ 、 Ｎｉ、 Ｃｕ 、 Ｚｎ 、 Ｃｄ 、 Ａｌ、 Ｍｎ 的新方法。研究了溶液酸度、试剂浓度、萘用量以及共存离子对待测物回收率的影响。方法可用于生物标准样品的测定,分析结果满意。     

Spectrophotometry Determination of Iron(II) Separated by Means of Adsorption of Its 3-(2-Pyridyl)-5, 6-Diphenyl-1, 2, 4-Triazine Complex with Tetraphenyl-Borate on Microcrystalline Naphthalene

A procedure is describe for the adsorption of ion-associated complex of iron(II) 3-(2-pyridyl)-5, 6-diphenyl-1, 2, 4-triazine (abbreviated as PDT) cation with tetra phenylborate (TPB) anion on macrocrystalline naphthalene. A water-insoluble ion-associated complex formed with PDT and TPB is quantitatively adsorbed on micro-crystalline naphthalene. The solid mixture containing the colored complex is dissolved in acetonitrile and the absorbance was measured at 553 nm. The other factors such as pH, amounts of reagents and naphthalene, shaking and standing times, diverse ions are studied. The method has been applied for the determination of iron in alloys and water samples.     

Column Preconcentration of Palladium Using Phenanthrenequinonedioxime Supported on Naphthalene by Atomic Absorption Spectroscopy

Abstract

A solid chelating compound, phenanthrenequinonedioxime(PQDO) supported on naphthalene provides a rapid and economical means of preconcentration of palladium from the aqueous samples. Palladium forms a complex with PQDO supported on naphthalene in the column at pH 1.2～2.7. The metal complex and naphthalene are dissolved out from the column with 5 ml of dimethylformamide-nitric acid (100+4) and the absorbance is measured atomic absorption spectrometer at 244.7 nm. A calibration curve is linear over the concentration range 1～24 μg of palladium in 5 ml of the final solution. The sensitivity for 1% absorption is 0.126 μg/ml (0.153 μg/ml for the direct AAS method from the aqueous medium). The method has been used for the determination of palladium in various synthetic samples and can be safely applied to the environmental samples too.     

Determination of bismuth by flame atomic-absorption spectrophotometry after separation by adsorption of its 2-mercaptobenzothiazole complex on microcrystalline naphthalene

Trace amounts of bismuth have been determined by atomic-absorption spectrophotometry after adsorption of the 2-mercaptobenzothiazole complex on naphthalene. The method has been applied to the determination of bismuth in aluminium alloys.     

Analysis of metals by solid-liquid separation after liquid-liquid extraction spectrophotometric determination of palladium(II) by extraction of palladium dimethylglyoximate with melted naphthalene

A method of liquid-liquid extraction of palladium di-methylglyoximate with molten naphthalene followed by solid-liquid separation is successfully applied to palladium. The complex between palladium and dimethylglyoxime is easily extracted into molten naphthalene. After extraction, the very fine solidified naphthalene crystals are dissolved in chloroform, and the absorbance of the resultant solution is measured at 370 nm against a reagent blank. Beer's law is obeyed for 30-370 mug of palladium in 10 ml of chloroform, and the molar absorptivity is calculated to be 1.72 x 10(4) l.mole.(-1)mm(-1). Various alkali metal salts and metal ions do not interfere. The interference of nickel(II) is overcome by the extraction at pH 2, and that of iron(III) by masking with EDTA or by reduction to iron(II). The method is rapid and accurate.     

Spectrophotometric determination of cobalt in a vitamin, alloys and an ore by extraction of its 3-hydroxy-2-methyl-1,4-naphthoquinone 4-oxime complex into molten naphthalene

A selective spectrophotometric method has been developed for the determination of cobalt after extraction of its 3-hydroxy-2-methyl-1,4-naphthoquinone 4-oxime (HMNQM) complex into molten naphthalene. The optimum pH range for the extraction is 5.0-7.5. The solidified naphthalene, containing the cobalt-HMNQM complex, is separated by filtration and dissolved in N,N-dimethylformamide. The absorbance is measured at 430 nm against a reagent blank. Beer's law is obeyed up to 1.90 ppm cobalt. The molar absorptivity is 2.09 x 10(4) l.mole(-1).cm(-1).     

微晶萘固相反射散射分光光度法测定钼的研究

研究了微晶萘萃取钼与吡咯烷基二硫代甲酸铵配合物的条件,并设计了固相反射散射分光光度法直接测定萘相中钼的含量。方法有较好的选择性,可以在钨存在下直接测定地质样品中钼的含量,方法检出限为０．０２３μｇ／ｍｌ相对标准偏差为４．２％。     

Application of the Ion Pair of 2-(5-Bromo-2-pyridylazo)-5-diethylaminophenol and Ammonium Tetraphenylborate for Preconcentration of Trace Vanadium and Determination by Third Derivative Spectrophotometry

ＩｎｔｒｏｄｕｃｔｉｏｎＶａｎａｄｉｕｍｉｓｏｎｅｏｆｔｈｅｍｏｓｔｉｍｐｏｒｔａｎｔｅｌｅｍｅｎｔｗｈｉｃｈａｆｆｅｃｔｓｔｈｅｐｈｙｓｉｃａｌｐｒｏｐｅｒｔｉｅｓｏｆｓｔｅｅｌ,ａｌｌｏｙｓａｎｄｈｉｇｈｐｕｒｉｔｙｍｅｔａｌｓ .Ｉｔｉｓｗｉｄｅｌｙｄｉｓｔｒｉｂｕｔｅｄｉｎｔｈｅｅａｒｔｈ’ｓｃｒｕｓｔ,ａｎｄｉｔｓｃｏｍｐｏｕｎｄｓｃａｎｂｅｈｉｇｈｌｙｔｏｘｉｃｔｏｍａｎａｎｄａｎｉｍａｌｓａｎｄｃａｕｓｅｅｎｖｉｒｏｎｍｅｎｔａｌｄｉｓｅａｓｅｓｗｈｅｎｒｅｌｅａｓｅｄｉｎｔｈｅａｔｍ…     

微晶萘固液萃取分离和ICP-AES测定痕量金的研究

在一定酸度的盐酸介质中,络阴离子ＡｕＣｌ－４与孔雀绿（ＭＧ）形成稳定的离子缔合物,可被析出的微晶萘定量吸附,实现痕量金的分离与富集。分离了基体富集物中的Ａｕ,并用ＩＣＰ－ＡＥＳ测定。详细考察了影响金的分离与测定的各种因素。在优化的实验条件下,方法的检出限为６．０ｎｇ／ｍＬ,ＲＳＤ为１．３４％（ｎ＝９）。本法已用于矿石浸取液和标准矿样中痕量金的测定,分析结果满意。     

Interaction between carbon dioxide and naphthalene: A molecular modeling approach

The formation of a charge-transfer complex between carbon dioxide and naphthalene was studied using a molecular modeling program, with the aim of studying the solubility of naphthalene in supercritical carbon dioxide. The orbitals involved in the formation of the complex were studied using MINDO/3 as the semi-empirical method. A solvent cage was constructed, and the maximum number of carbon dioxide molecules to surround naphthalene was found to be 20. The heat of interaction of the complex was obtained using MINDO/3. © 1994 by John Wiley & Sons, Inc.     

Spectrophotometric determination of copper in environmental samples by solid-liquid extraction of its 9, 10-phenanthrenequinone monoximate complex into molten naphthalene

A fairly selective and sensitive spectrophotometric method has been developed for determination of copper after extraction of its 9, 10-phenanthrenequinone monoximate complex into molten naphthalene in the pH range of 6.1-8.4. At room temperature, the solid naphthalene containing the metal complex is separated by filtration, dissolved in dimethylformamide (DMF) and the absorbance measured at 470 nm against the reagent blank. Beer's law is obeyed in the concentration range, 0.0-9.6 micrograms of copper in 10ml of DMF. The molar absorptivity and sensitivity are 6.30 X 10(4) 1 mol-1 cm-1 and 0.001 micrograms cm-2, respectively. The interference of various ions has been studied and the method has been applied for the determination of copper in various standard reference materials, beers, wines, human hair and environmental samples.     

Studies on Cyclodextrin Inclusion Complex by Fluorescence Anisotropy

An equation for determining the equilibrium association constant (KA) of cyclodextrin inclusion complex with fluorescence anisotropy is derived and used to determine KA of pyrene-B-cyclodextrin inclusion complex. The existing forms of cyclodextrin inclusion complex in solution, the interaction type of host with guest, and the possibility of application of B-cyclodextrin in the analysis of metal ions using naphthalene derivative as a ligand are discussed based on the equation derived along with the curve of fluorescence anisotropy versus cyclodextrin concentration of guest/cyclodextrin system.     

Time resolved fluorescent analysis for sealed heating of dimethyl-β-cyclodextrin and naphthalene system

The inclusion process of naphthalene into heptakis-(2,6-di-O-methyl)--cyclodextrin (DMCD) during the sealed heating was investigated by using solid state time,resolved fluorescent analysis. Fluorescence lifetimes of naphthalene in naphthalene crystals and in inclusion complex with DMCD prepared by coprecipitation were determined 59 ns and 88 ns, respectively. Fluorescence lifetime of naphthalene monomer becomes longer after inclusion complex formation. Fluorescence lifetimes of naphthalene monomer and excimer in the sealed heating complex were determined about 80 ns and 100 ns, respectively. By setting the observing wavelength of time resolved fluorescent analysis at 355 nm, the formation and the decay of the excimer state of naphthalene during the sealed heating process were successfully confirmed.     

Spectrophotometric determination of nickel after separation by adsorption of its alpha-furildioxime complex on naphthalene

A new method is proposed for collecting traces of nickel from aqueous solution by precipitation as the alpha-furildioxime complex and adsorption of this onto microcrystalline naphthalene. The precipitate is collected, dried, and dissolved in chloroform, and the nickel is determined spectrophotometrically at 438 nm. The linear calibration range is 2-35 mug/10 ml. The molar absorptivity is 1.6 x 10(4) l. mole(-1). cm(-1). The main advantage is that the nickel is collected quantitatively after only a few seconds'shaking. The effect of varying pH, amount of reagent, naphthalene or buffer, shaking and standing time, and interferences have been investigated.     

Study of Reactivity of a Chain-Bound Molecular Moiety by Intermolecular Exciplex Formation

The effect of chain-binding on the reactivity of naphthyl groups towards intermolecular exciplex formation with triethylamine has been investigated. Polyamides of 2,6-bis(N-methyl methyl-amino)naphthalene with the diacid chlorides ClOC(CH₂)_x COCl (x = 2, 4, 6, and 8), designated P-2, P-4, P-6 and P-8, and 2,5-bis(n-methyl N-acetyl methylamino)naphthalene (MC) have been studied. Fluorescence spectra of dilute solutions of the poly-amides and their model compound have been obtained in the presence of varying amounts of triethylamine (TEA) as a quencher. The variations of exciplex monomer fluorescence intensity ratio, I_E/I_M, with quencher concentration indicates the following reactivity order: MC > P-8 > P-6 ± P-4 > P-2, which reflects the relative diffusion rate and accessibility of the naphthalene moiety. This order also represents the relative chain flexibilities of the polyamides studied. Monomer fluorescence quenching is explained in terms of a scheme involving formation of an exciplex, and a nonfluorescent CT encounter complex. Stern-Volmer plots of monomer fluorescence quenching reveal an anomalous order where the monomer fluorescence of the model compound is less effectively quenched. This may imply a slower dissociation rate constant of the nonfluorescent encounter complex in the case of the polymers.     

Application of the Lee-Wheaton conductance equation to the problems of the ionization of bisulfate ion and of HF in water

The applicability of the Lee-Wheaton conductance equation to the problem of accounting for the variation of the conductivity of moderately complex electrolyte solutions containing more than two kinds of ionic species and involving one or more ion-association equilibria is demonstrated using the chemically interesting examples of sulfuric acid, sodium bisulfate, and hydrofluoric acid, as well as naphthalene trisulfonic acid, sodium naphthalene trisulfonate, and lanthanum naphthalene trisulfonate. The question of retention of the C7 and V2 terms in the Lee-Wheaton equation is discussed.     

Investigation of the Benzene–Naphthalene and Naphthalene–Naphthalene Potential Energy Surfaces: DFT/CCSD(T) Correction Scheme

The potential energy surfaces of the naphthalene dimer and benzene–naphthalene complexes are investigated using the recently developed DFT/CCSD(T) correction scheme [J. Chem. Phys. 2008 , 128, 114 102]. One and three minima are located on the PES of the benzene–naphthalene and the naphthalene dimer complexes, respectively, all of which are of the parallel‐displaced type. The stabilities of benzene–naphthalene and the naphthalene dimer are ?4.2 and ?6.2 kcal mol^?1, respectively. Unlike the benzene dimer, where the T‐shaped complex is the global minimum, the lowest‐energy T‐shaped structure is about 0.2 and 1.6 kcal mol^?1 above the global minimum on the benzene–naphthalene and the naphthalene dimer potential energy surfaces, respectively.     

Determination of trace levels of manganese in various biological and environmental samples by atomic absorption spectrometry after solid-liquid extraction and preconcentration with the ion pair formed by the nitroso-S anion and the tetradecyldimethylbenzylammonium cation.

Manganese is quantitatively retained by 2-nitroso-1-naphthol-4-sulfonic acid (nitroso-S) and tetradecyldimethylbenzylammonium (TDBA) chloride on microcrystalline naphthalene in the pH range 9.5-10.6 from large volumes of aqueous solutions of various samples. After filtration, the solid mass consisting of the manganese complex and naphthalene is dissolved in 5 mL dimethylformamide and the metal is determined by flame atomic absorption spectrometry. Alternatively, the manganese complex can be quantitatively adsorbed on TDBA-naphthalene adsorbent packed in a column and determined similarly. About 0.2 microg manganese can be concentrated in a column from 400 mL aqueous sample with a concentration as low as 0.5 ng/mL. Eight replicate determinations of manganese at 0.8 microg/mL gave a mean absorbance of 0.156 for the final solution with a relative standard deviation of 1.4%. The sensitivity for 1% absorption was 23 ng/mL. The interference of a large number of anions and cations was studied, and the optimized conditions developed were used for trace determinations of manganese in various alloys, and in biological and environmental samples.